Home > Publications database > Ballistische Tieftemperatur-Josephson-Kontakte auf der Basis hochbeweglicher zweidimensionaler Elektronengase |
Book/Report | FZJ-2019-04550 |
1998
Forschungszentrum Jülich, Zentralbibliothek, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/22646
Report No.: Juel-3607
Abstract: During this thesis ballistic low-temperature Josephson-contactes based on niobium-twodimensional electron gas (2DEG)-niobium structures were designed and fabricated. In order to analyse the influence of the sample preparation on the electronic properties ofthe niobium-semiconductor interface, IV-curves of single interface junctions were measured. We described the results in terms of an extension of the model by Blonder, Tinkham and Klapwijk (BTK). The Josephson-contacts based an an AlGaSb/InAs-heterostructure showed a supercurrent, which was tunable by an additional current injected via an ohmic contact into the 2DEG. The energy dependence of the suppression of a supercurrent by the injected carriers was measured in a four-terminal configuration. By comparing this result with an effective temperature approach a thermalization of the injected carriers could be excluded. In a three-terminal configuration the supercurrent was switched off locally, which was proven by simulating the measured Fraunhofer- patterns. The niobium-InGaAs/InP-niobium samples which also showed supercurrents were examined with respect to phasecoherent transport at finite bias. The observation of fractional Shapiro-steps gave a strong hint to a deviation of the current-phase relation from the sinusodial shape as expected for ballistic Josephson-contacs.
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